Thread twisting apparatus



Feb. 27, 1962 w. LENK THREAD TWISTING APPARATUS 2 Sheets-Sheet 1 FiledAug. 3, 1960 FIG?) m E ML M V S H H W ATT'YS W. LENK THREAD TWlSTINGAPPARATUS Feb. 27, 1962 2 Sheets-Sheet 2 FIG.6

Filed Aug. 3, 1960 FIG. 8

FIG.9

INVENTOR: WILHELM LEN K ATT'YS United States Patent 3,022,623 THREADTWISTING APPARATUS Wilhelm Lenk, Remscheid-Lennep, Germany, assignor toBarmer Maschinenfabrik Aktiengesellschaft, Wuppertal-Elberfeld, GermanyFiled Aug. 3, 1960, Ser. No. 47,204 Claims priority, application GermanyNov. 17, 1959 Claims. (Cl. 5758.83)

This inven ion relates to thread twisting apparatus, and moreparticularly, to an improved apparatus or device for drawing off andtwisting equal lengths of thread from a pair of bobbins or feed spoolswhich are superimposed and rotate on the same axis. The improvement ofthe invention is especially advantageous in combination with theso-called double twist twisting machine, sometimes referred to as amultiple twist or two-for-one twisting machine.

in the usual textile apparatusfor twisting two threads together, e.g. ina double twist twisting machine, it has been a common practice to drawthe threads from a single bobbin or feed spool thread package and thenfeed the combined threads directly into the twisting device. In thisprocess, however, it is essential that the threads first be wound uponthe single feed spool with as equal and uniform a tension as possible.Otherwise, it is impossible to draw off the threads with equal lengthsand proper alignment for twisting. This preliminary step of prewindingthe feed spool is both time consuming and difficult to achieve,especially in the commercial handling of a large volume of thread.

In order to avoid the prewinding step, it has been proposed that twofeed spools be employed instead of the single prewound spool, and thatthese two spools be mounted on a common spool carrier for free andindependent rotation on the same spindle. The threads drawn otfseparately from each bobbin or spool are then joined in preparation fortwisting. In this case, the problem is essentially one of drawing theindividual threads from each spool at a constant and mutually uniformrate of speed such that the lengths of thread are equal throughout thedrawing off and twisting operations. With unequal thread lengths, thelonger thread tends to turn or loop around the shorter thread duringtwisting so as to give an imperfect product as evidenced by an excess.of thread in the form of a twisted loop, also referred to as a corkscrewor tangle. Thus, if the thread lengths are not accurately controlled insome fashion, there is a very undesirable formation of a slack threadand the resulting product is a ribby or knotted yarn.

In the development of the present invention it was found that in theprocess of drawing the individual threads from each bobbin to a fixedpoint acting as a thread guide member, the bobbins tend to rotate atdifferent speeds, i.e. to run ahead or lag behind one another. Thistendency cannot be entirely avoided even it the bobbins have exactly thesame diameter because the rotating speed of the individual bobbin doesnot remain uniform.

Upon further investigation it was found that the nonuniform rotation ofeach bobbin and their non-synchronized rotation with resultingdifferences in thread length is due primarily to the fact that thethread take-off point on each bobbin follows a locus on a surface lineof the bobbin parallel to and relatively stationary With respect to thebobbin aris. Thus, in the original winding of the bobbin, the threadtraverses the bobbin along its axis and reciprocates from one end to theother. Likewise, if the thread is then drawn oil to a relatively fixedpoint, the thread reciprocally traverses the bobbin from one end to theother, and the point at which the thread is lifted or withdrawn from theouter thread wound surice face follows the same linear path, referred toas the thread take-01f locus.

In drawing off the thread to a fixed guide member, such as an eyelet orthe like, located intermediate the ends of the bobbin, the thread pathpasses through or defines a thread run-oh or traversing triangle havinga base corresponding to the thread take-off locus and an apexcorresponding to the fixed guide member. The opposite sides of thetriangle are determined by the thread path at the outermost ends of thethread traversing movement on the bobbin. It will be readily observedthat if the fixed guide member is located only a short distance from theouter peripheral surface of the bobbin, the thread path between thetake-off point and the guide member will be quite short when the threadis perpendicular to the take-off locus or base of the run-oft triangleand quite long when the thread reaches the ends of the bobbin. Thisditr'erence in thread length between the take-. off point and the guidemember naturally causes the rotational speed 'of the bobbin to changeeven though the thread is drawn 01f at a constant rate. By working withtwo bobbins and drawing a thread from each bobbin at the sarrie rate,the rotational speed of the bobbins will be different unless thetraversing motion of the thread is identical in both cases besidesemploying bobbins with the same diameter. However, this method ofoperating is not feasible, and in any event, would require a verycareful prewinding of each of the bobbins as in the case of the singlebobbin.

One object of this invention is to provide an improvement in threadtwisting apparatus wherein equal lengths of thread can be drawn off fromtwo bobbins and then joined for twisting.

Another object of the invention is to provide improved apparatus fordrawing off and twisting equal lengths of thread which are unwound fromtwo bobbins independently rotating on the same axis, especially incombination with a double twist twisting machine.

Another object of the invention is to avoid a preliminary bobbin windingstep by means of apparatus which will compensate for differences inbobbin diameter and the tendency for the bobbins to rotate at variableand diflerent speeds.

Still another object of the invention is to provide an improved threadtwisting apparatus which can be employed to draw off and twist equallengths of threads having different physical or dimensionalcharacteristics.

Yet another object of the invention is to provide a relatively compactthread twisting apparatus, especially a double twist twisting machine,readily adapted to commercial applications and capable of handling alarge volume of thread.

Another object is to provide thread twisting apparatus capable ofproducing a uniformly twisted thread or yarn product free of tangles,knots, slack threads and the like.

The foregoing and other important objects, advantages and functions ofthe invention will become more apparent in view of the followingdescription which, taken in conjunction with the accompanying drawings,discloses the preferred features of the invention.

In the drawings:

FIG. 1 is a side elevation and partly schematic view with portions cutaway of a double twist twisting machine in combination with theimprovement of the invention;

FIG. 2 is a top plan view of the bobbin holding device shown in FIG. 1;

FIG. 3 is a roll out view of the thread path and its associated guidemembers from the thread take-off locus on one of said bobbins to a fixedguide element at the apex of the thread run-off triangle;

FIG. 4 is a side elevational view corresponding to the twistingapparatus disclosed in FIG. 1, but illustrating -a different brakingmechanism;

FIG. is a top plan view of the bobbin holding device shown in FIG. 4;

FIGS. 6, 7 and 8 are side elevational views illustrating various brakingelements in accordance with the invention; and

FIG. 9 is an enlarged view of an adjustable spring tensioned shaft ortube adapted to urge a braking element against the bobbins. i

'The same numerals are employed to designate similar parts inthe variousfigures of the drawings; It will be understood that the bobbin holder orframe need not be mounted in a vertical position as might otherwise besuggested by the drawings.

The above-mentioned objects are achieved in accord ance with the presentinvention by providing in combination with a thread twisting apparatusfor drawing off and twisting equal lengths of thread from a pair ofsuperimposed or adjacently mounted bobbins independently rotating on acommon axis, thread run-off guide means for each bobbin including arelatively fixed guide element at the apex of the thread run-01ftriangle, and a plurality of thread guide rods mounted substantiallyparallel to the bobbin axis at spaced intervals between the threadtake-01f locus of the bobbin and the apex guide element. The threadguide rods are adapted to engage the thread in runing contact, i.e. inthe running direction of the thread as it is drawn off, and also intraversing contact, i.e. in a reciprocal. movement of the thread alongthe elongated surface of the rod. Together with the apex guide element,

the guide rods are also adapted to maintain the thread adjacent to butout of contact with the outer peripheral surface of thebobbin, e.g, at arelatively short distance of preferably not more than about one-halfthe. radius of the fully wound bobbin. In addition the distance of thethread path from the take-off locus, over the rods to the apexshould beat least about twice, preferably at least three times, the height of thebobbin. In the same combination of a thread twisting apparatus,particularly of the type referred to as a double twist twisting machine,it is highly advantageous to include a braking means adapted toresiliently engage a peripheral surface of each of the bobbins,i.e. withmeans to urge a separate or combined braking surface for frictionalengagement against the bobbins. Such brakingmeans combined with thethread guide means of the invention are effective to provied a uniformrate of rotation for the bobbins whereby equal thread lengths can bedrawn off and twisted. Also, the braking means can be designed foradjustment to bobbins of different diameters and the frictional surfaceand/ or braking pressure can be advantageously adapted to threads havingdifferent physical or dimensional characteristics. These featuresfalling within the scope and purpose of thepresent invention are morefully explainedhreinafter.

In constructing the apparatus of the present invention, a principalproblem was to avoid the variable rate of rotation of the bobbins causedby drawing the thread from the take-off locus directly to an apex guideelement situated very close to the bobbin. As noted above, thisarramgement of the apex with a constant drawing olf speed of the threadresults in a very uneven bobbin rotation be- I fore, the arrangement andconstruction of the apex guide element and thread guide rods of thisinvention are especialy useful in a double twist twisting device'becausethese guide means can all be located within the boundary defined by therotating balloon.

The term bobbin is employed herein to describe a thread wound spool,i.e. both the spool and its thread package which is unwoundor drawn offin the usual fashion during the, thread twisting operation. The termthread is employed herein to include various fiber forms includingyarns, strings, tows, a monofilament, filament bundles and the like. Thefibers may be natural, artificial or synthetic, and the thread may becomposed of continuous filaments or staple fibers.

.Referring' now to the drawings, FIG. 1 illustrates a double twisttwisting machine as a particularly preferred embodiment of theinvention, shown partly in schematic form with certain conventionalportions omitted. In this machine a stationary frame is provided byspool carrier land various elements connected thereto. .The spoolcarrier 1 ismaintained in a stationary position in a concause of anextremely large variation in the length of the bobbin i.e. in adirection perpendicular to the bobbin axis as indicated by FIG. 3,disregarding the guide rods shown therein and assuming that this,figure. isla simple ventional manner, e.g by means of an eccentricweightlocated on one side of the carrier while inclining the machine fromthevertical position shown. A stationary spool carrier can also beachieved by mounting one or more magnets around the carrier at as'uflicient distance therefrom to permit passage of the ballooningthread T. These magnets are placed opposite other magnets in or on thespool carrier itself, and the attraction between opposing magnets holdsthe carrier in place. Since these means of holding the carrierstationary have become quite standard in the art, the drawings have beensimplified to avoid showing the corresponding elements of the apparatus.

A hollow spindle 2 extends above the spool carrier 1 and carriesrotatably thereon two separate hollow spoolreceiving holders 3 and 4which fit tightly into two bobbin spools 5 and 6 which in turnrespectively carry thread packages 7 and 8. The bobbins are wound suchthat the spools must rotate on the spindle as the thread is drawntherefrom and such that the thread reciprocally traverses the bobbinfrom one end to the other.

A stable basket frame is completed by the side support 9Jconnecting thespool carrier 1 to'the upper ring 10. As further members of thisprotective basket frame, located outside the circumference of thebobbins or thread packages 7 and 8 there is mounted around the same axisas the spindle and substantially parallel thereto a turnable rod ortubular carrier 11 seated at either end for rotation on its axis, forexample by the prong or pin 12 to the spool carrier 1 and by prong 13 tothe upper ring 10, and in addition, the thread guide bars.

or rods 14 and 15, likewise arranged to rotate or turn about their axisby means of a prong or pin at either end.

On the tubular carrier 11, there is connected or mounted in a relativelyfixed position a series of thread guide elements in the form of eyeletsor books 16, 17 and 18, and there is also mounted two friction straps orshoes :19 and 20. V l

The tubular carrier or rod 11 is arranged adjacent the periphery of thethread packages 7 and 8 such that the eyelets 16 and 17, positionedintermediately the height of the bobbins, are situated at 'a distancefrom the middle take-off point 30 of thethread locus L of more than.three times the height h of the thread package elevational view ratherthan a roll out View. However, V such an arrangement would require avery large Opera:

tional space which would be especially undesirable: in commercialoperations requiring a large thread volume or bobbins 7 and 8. Thisarrangement is most clearly shownby the roll out view of FiG 3, butcanvalso he I tragedon the threadpath. in FIG; 2.

Furthermore, the tubular carrier 11 is spring urged to rotate the brakeflanges 19 and 20 by means of a torsion spring 21 against the threadpackages 7 and 8. However, if desired, the brake flanges can bepivotally rather than fixedly mounted on the tubular carrier, and eachflange can then be spring urged by means of its own torsion spring, coilspring, leaf spring or the like.

It is preferable to provide an adjustable spring tension, 7

e.g. as hereinafter discussed with respect to FIG. 9, and various meanscan be adopted for this purpose within the scope of the invention.

At the upper end of the spool carrier 1 and attached to the spindle 2 bymeans of an extension or carrying arm 22 is a thread guide roller 23.The lower portion of the double twist twisting device is constructed inthe usual manner so as to provide a reserve disc 24 which rotatestogether with the operatively driven whorl 25. The spindle '2 islikewise designed in the usual manner with a hollow core 26 and apassageway or opening 27 leading to the reserve disc 24.

During operation, the combined threads T are drawn off individually andlaterally from each bobbin 7 and 8, as indicated by the broken lines 28and 29, and in running and traversing contact over the thread guide rods14 and 15. As illustrated in FIGS. 1 and 3, the traverse position ofthreads on the bobbins are at their lower extremity on the thread locusL, the upper extremity of the traverse position of the thread on bobbin7 being indicated by dotted line 31. The individual threads are then ledthrough the substantially fixed apex eyelets 16 and 17, the threadsbeing joined at the upper eyelet 17. From this point, the threads areconducted in common through eyelet 18, over the roller 23 around theupper end of the spool carrier and downwardly through the hollow core 26of spindle 2, and thecombined threads are then drawn outwardly onto thereserve disc 24, all in the conventional manner of a double twisttwisting machine. The thread as it emerges from the reserve disc 24 isled outwardly in a rotating balloon T around the end of the bobbins,through an eyelet or similar guide means 32, over a preliminary draw-offroll 33 and onto a take-up reel or draw-oil rolls 34 and 35. Theselatter rolls represent the point at which drawing or unwinding of thethreads from the bobbins originates. In operation, these rolls areoperated to obtain a substantially uniform drawing-off speed. The twofriction straps 19 and 2G bear with the same pressure against the threadwound circumference of the bobbins 7 and 8 and are generally sufficientto synchronize the rotational spread of bobbins having approximately thesame diameter with the aid of the thread guiding means of the invention.

Because the thread guide eyelets 16 and 17 are located at asubstantially extended distance from the thread take-0E locus L, theresulting thread path forms an extended run-otf triangle as defined bythe. base L and apex 16 in FIG. 3. In this extended triangle, there isonly a slight variation of the thread length between the locus L and theapex 16 as the thread take-off point reciprocates on or traverses thebobbin 7. Accordingly, with a uniform thread running speed imparted bydraw rolls 34 and 35, the rotational speed of the bobbins is maintainedsubstantially equal, especially with the aid of the braking forcesapplied by straps 19 and 29. The usual diiferences in thread tension andlength between the two twisted threads is thus diminished to such anextent that even the very finest threads and yarns can be twistedwithout difiiculty.

With reference to FIGS. 4 and 5, the double twisttwisting machine andthread guiding means of the present invention are reproducedsubstantially as disclosed in FIGS. 1-3. However, the braking meansillustrated here represent an especially preferred embodiment or featureof the invention, with other alternative embodiments be- H ingillustrated in FIGS. 6-8.

In these embodiments, the tubular carrier or rod 11 has attached theretoand at right angles and about midway between the ends of each bobbin, aswinging arm or shaft 36 adapted to pivotally receive a U-shaped,V-shaped or Y-shaped yoke with two oppositely disposed arms 37 and 38.The pin or yoke handle it at the base of the yoke is seated to turn inthe swinging arm 36. At the free ends of the arms and in a position tofrictionally engage a peripheral or circumferential surface of thebobbins 7 and 8, there are mounted, preferably in removable orinterchangeable fashion, a pair of brake shoes or arcuate shaped brakingsurfaces 39 and 40.

The tubular carrier 11 is pretensioned by means of a torsion spring 21and is caused to rotate or spring urged about its own axis together witharm 36, thereby pressing the brake shoes 39 and 4t} inwardly against oralong a circumferential surface area of the two bobbins. The pivotlinkage or pivotal joint formed by yoke-handle or pin 41 and arm 36,assures that both brake shoes will engage their respective bobbinsregardless of minor differences in the diameters of the bobbins.

In FIGS. 4 and 5, the brake shoes 39 and 40 are represented as merelyextensions of the yoke arms 37 and 38 and are given a fiat arcuateshape, the surface contacting the bobbin being relatively smooth.

In FIG. 6, the brake shoes 42 and 43 are shown in side elevationexposing the bobbin engaging surfaces of the shoes, which in this caseare relatively flat smooth surfaces. The brake shoes are preferablyadapted to be interchanged on the free ends of the yoke arms 37 and 38.In this Way, brake shoes having a rough, uneven, ribbed or cross-hatchedsurface can be exchanged to obtain a smaller or greater frictionaleffect, e.g. as illustrated by brake shoes 44 and 45 in FIG. 7.

Likewise, it is possible to mount a rotatable ball or roller as a brakeshoe on each of the opposed yoke arms, and these rotating brakingelements can be further provided with magnetic or similar means toinhibit their free revolution and thereby provide an adjustablefrictional or bearing force against the bobbins. It is also advantageousto employ a roller means as disclosed in my copending application,Serial No. 859,943, filed December 16, 1959, the disclosure of which isincorporated herein by reference thereto. Such adjustable and brakecompensating devices are especially useful when drawing ofli andtwisting threads of different origin or different thickness or surfacetexture. Thus, synthetic threads and natural threads, each of adifierent filament diameter can be twisted together and subsequentlyprocessed to give special eifects. Where the brake shoes have a highdegree of adjustment or a compensating roller or rollers are employed,these elements alone are usually sufficient to draw ofif and twistsubstantially equal thread lengths, even without the thread guidingmeans forming an extended run-oft triangle according to the presentinvention. In these cases, for example, the thread can be drawn directlyfrom the bobbin 7 or 8 to the guide eyelets 16 and 17 without engagingany other thread guiding means. The thread path otherwise remains thesame.

An especially preferred braking means in accordance with this inventionis illustrated in FIG. 8. The spring urged carrier tube 11 again has aswinging arm 36 fixed thereto, but the yoke connecting pin 41 seated toturn in the arms 36 has two laterally extending legs 48 and 49 so as toprovide a T-shaped base for the yoke. The brake shoes 46 and 47 aremounted at the free ends of oppositely disposed slotted arms 37 and 38',and these arms in turn are adjustably connected to the T-shaped baselegs 48 and 49 by means of wing flanges 50 and 51. With respect to eachbrake shoe, the slot of the brake shoe arm is engaged for adjustment ofits length by a tightening screw or nut and bolt combination 52 and 53connecting said arm to one wing of the flange. At the same time theother wing of the flange is adjustably mounted by means of a tighteningscrew 54 and .55 received by the legs 48 and 49 of the yoke base. Thisconmruction permits the brake shoes 46 and 47 to be adjusted to anyposition with reference to the circumferential surfaces of the bobbins,and further permits a different leverage or pressure on each bobbin eventhough the swinging arm 36 is urged inwardly with a single springtension. 7

In FIG. 8, the brake shoes are shaped as a3-sided or triangular prism asindicated in the end view thereof and are mounted'for adjustablerotation at the ends of the arms 37 and 3%. In this way, each of thethree brak ing surfaces 56, 57 and 58 can be given a difierent surfacetexture or degree of roughness, thereby permitting a dilferent selectionof frictional forces as a braking surface applied to each bobbin. Incombination with the adjustable positions of the brake shoes, withrespect to the spindle or bobbin axis as discussed in the precedingparagraph, the further provision of, 3-sided brake shoes permits a Widevariation in frictional forces. This entbodiment is therefore especiallyuseful where there is-a great difierence in bobbin diameters or whereentirely different types of thread are employed on each bobbin, becausethese differences can be readily equalized with adjustment of the brakecontact pressure or frictional effect on the bobbins.

In order to provide different spring tensions on the carrier tube 11,the spring device shown in the enlarged view of FIG. '9 is particularlysuitable. The spring 21 is seated at one end in the annular fiange59 oftube 11 and at its other end in the adjusting ring or collar 60 which isfree to rotate about the tube 11 and which can be clamped in anypredetermined position by means of the adjustment screw 61. A scale canbe marked on the ring 60 to provide a measurement for the requiredtension values.

It is also possible to provide an adjustable tensioning means in theform of a draw or coil spring secured at one end to alever armprotruding from the end of tube 11 above or below the base plate carrier1 and secured at the other'end by means of a hook on the spring attachedin any one of a series of holes in the base plate 1. Other springtension means will be readily apparent to one skilled in the art withoutdeparting from the spirit and scope of the present invention.

This invention is not limited to a double twist twisting machine or to adevice containing only two bobbins. Other thread twisting apparatus withtwo or more feed spools or bobbins can be readily adapted to theprinciples herein disclosed, it being understood that at least twobobbins are employed and at least two threads of equal length aretwisted together. Thus, the invention can be readily adapted to theso-called rim-twisting type of machine or to other thread twistingdevices by extending the spindle to receive more than two bobbins or bya parallel series of pairs of bobbins interconnected to accomplish thesame functions. For example, .by adding a turntable linking arm betweenthe swinging arms 36 of two of the thread twisting devices, each with apair of bobbins, the number of bobbins can be increased to four, and theleverage ratio between the various brake shoes can be readily adjustedfor all required contact pressures. In this case, it is helpful toconnect the swinging arm 36 to the tube 11 such that this arm can beadjusted to difierent positions along the length of the tube.

In essence, the present invention gives improved combinations andsub-combinations of apparatus in thread twisting devices, whereby equalthread lengths can be withdrawn and twisted from two or more bobbins togive a uniformly twisted product. A prewinding of the feed bobbins canbe completely avoided, and the necessary apparatus can be contained in aminimum space for large commercial volumes of thread. The apparatus ofthe invention is particularly advantageous in combination with doubletwist twisting machines becauseit can be contained within the rotatingthread balloon. The inpair of superimposed bobbins independentlyrotating on a common axis, thread run-off guide means for each bobbincomprising a relatively fixed guide element at the apex of a threadrun-off triangle, and a plurality of straight thread guide rods mountedsubstantially parallel to thebobbin axis and parallel to each other atspaced intervalsbetween the thread take-off locus of said bobbin andsaidapex guide element, said rods being a daptedto engagesaid thread inrunning and traversing contact thereover' and together with said apexguide element to maintain the thread adjacent to but out of contact withthe outer' peripheral surface of said bobbin, the distance of the threadpath from said take-oft locus, over said rods to said apex guide elementbeing at least'twice the height of the bobbin.

2. In a thread twisting apparatus for drawing ofi and twistingequallengths of thread from a pair of super-- imposed bobbinsindependently rotating on the same axis,

the improvement which comprises: a spindle upon which. said bobbins arerotatably mounted; a stationary framehaving oppositely disposed supportsat the ends of the superimposed bobbins; means to hold said supports ina stationary position for rotation of said bobbins therebetween; andthread guide means defining a separate thread path for each of saidbobbins frorn the thread take-off locus of the bobbins, through arelatively fixed apex situated intermediately the ends of the bobbin andto a common point at which the threads from each bobbin are joined inpreparation for twisting, said thread guide means including a guideelement corresponding to said apex and a'plurality of straight threadguide rods mounted at eitherend to said supports substantially parallelto the spindleaxis and parallel to each other at spaced intervals aroundthe periphery of said bobbins between said thread takeoff locus andsaid'apex guide element, said rods being adapted to receive the threadfrom each bobbin in running and traversing contact thereover andtogether with said apex guide element to maintain the thread adjacent toand at a relatively short distance from the outer peripheral surface ofsaid bobbins, the distance of each thread path from said thread take-oillocus, over said rods to said apex guide element being at least twicethe height of the corresponding bobbin.

3. An improved thread twisting apparatus as-claimed in claim Zwhereinsaid thread guide rods are substantially cylindrical and free to rotateon their longitudinal axis.

'4. An improved thread twisting apparatus asclaimed in claim 2 providedwith braking means connected to said frame'and including means toresiliently urge a braking surface against a peripheral surface of eachof said bobbins.

5. An improved thread twisting apparatus as claimed in claim 4 whereinsaid braking means comprises a yoke having two oppositely disposedarms'pivotally mounted by means of a common shaft of said yoke, saidshaft being arranged transversely to said spindle axis on saidstationary frame for swinging movement in a plane approximatelyperpendicular to the spindle axis, a brake shoe mounted on each of saidarms, and means to resiliently urge said shaft toward said bobbins forfrictional engagement of said brake shoes thereagainst.

6. An improved thread twisting apparatus as claimed in claim 5 whereinsaid brake shoes are removably mounted on said arms, whereby brake shoeswith a different degree of surface roughness are interchangeablethereon.

7. An improved thread twisting apparatus as claimed in claim 5 whereinsaid yoke containsmeans for adjusting and securing the relative distanceof said brake shoes from said spindle for adaptation to bobbins havingsubstantially diflerent diameters.

8. In a double twist twisting machine, the improvement which comprises:a hollow spindle; means to receive two bobbins in a position adjacenteach other for independent rotation of said bobbins around the axis ofsaid spindle; a stationary frame having oppositely disposed supports atthe ends of the adjacent bobbins; means to hold said supports in astationary position for rotation of said bobbins therebetween; andthread guide means to lead a thread outwardly from each bobbin as saidthread unwinds from the thread take-oft locus of the bobbin, to furtherlead said thread from each bobbin through a relatively fixed apexsituated intermediately the ends of the bobbin and to a common guidemember where said threads are joined prior to twisting, and to lead thejoined threads around one end of said bobbins, through said hollowspindle and then outwardly in a rotating balloon around the other end ofsaid bobbins whereby a twist is imparted to said threads, said threadguide means including a guide element corresponding to said apex and aplurality of thread guide rods mounted at either end to said supportssubstantially parallel to the spindle axis at spaced intervals aroundthe periphery of said bobbins between said thread take-ofi locus andsaid apex guide element, said rods being adapted to receive the threadfrom each bobbin in running and traversing contact thereover andtogether with said apex guide element to maintain the thread adjacent toand at a relatively short distance from the outer peripheral surface ofsaid bobbins and within the boundary defined by said rotating balloon,the distance of each thread path from said thread take-ofi locus, oversaid rods to said apex guide element being at least twice the height ofthe corresponding bobbin.

9. An improved thread twisting apparatus as claimed in claim 8 whereinsaid thread guide rods are substantially cylindrical and free to rotateon their longitudinal axis.

10. An improved thread twisting apparatus as claimed in claim 8 providedwith braking means connected to said frame and including means toresiliently urge a braking surface against a peripheral surface of eachof said bobbins.

References Cited in the file of this patent UNITED STATES PATENTS1,995,533 Bochmann et al Mar. 26, 1935 2,504,020 Hanson Apr. 11, 19502,699,032 Landolt Jan. 11, 1955 FOREIGN PATENTS 594,542 Germany Mar. 19,1934 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,022,623 February 23" 1962 Wilhelm Lenk It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 3, line 47, for "provied" read provide line 55 for "hreinafter"read hereinafter column 7 line 57, for "turntable" read turnable Signedand sealed this 24th day of July 1962.

(SEAL) Attest:

ERNEST W SWIDEH DAVID L. LADD Commissioner of Patents Attesting Officer

